The Human
Body
Skeletal System
NPS/NAFL NORTH
NPSNAFLNORTH|
KOCL|May2021
Contents
The Human Body Page 3
The Skeletal System Page 4 - 10
Limbs Page 11 - 12
Joints Page 13 - 21
Muscles Page 22
Keep in Mind Page 26
Activities Page 28
Mind Buster Page 29
Vocabulary Page 30
The human body is a wonderfully efficient
and complex machine. It has organs and
systems that are specialized to perform
specific functions.
The stomach, the intestines, the liver and the
pancreas help with the digestion of food.
These organs make the Digestive system.
Lungs help in breathing. The lungs are one of
the most important organs of the Respiratory
system.
The system that helps you feel and react is
the Nervous system. The system that helps in
movement is the Locomotory system.
The Human Body
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A human adult has 206 bones, whereas a human child has more
than 350 bones. As a child grows, some of the bones fuse together.
The bones of the body are living
and need nourishment for their
growth and repair. Minerals like
calcium, phosphorous and
certain vitamins are important
for bones.
Bones differ in size and shape.
The bones of your fingers and
toes are small, but the bones of
your arms and legs are long.
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BONES
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Bones have a supply of blood vessels and nerves which grow as
you grow older. Bones are hollow and not solid. The inside of
bones contain a soft and spongy matter called bone marrow.It
has blood vessels.
Bone marrow is the body’s factory for producing red blood cells
and it also stores fat.
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BONES
The skull is a bony structure in our
body that protects the brain. In
adult human beings, the skull is
normally made up of 22 bones,
joined together to cover the brain
and give shape to it.
All the bones in the skull are fixed,
except the lower jaw, which is
movable. The movable jaw allows
us to talk and eat.
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SKULL
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The skeleton is the framework
of bones which gives shape to
the body and protects the
soft, delicate inner organs
such as the heart and lungs.
The skeleton also enables the
movement of the body.
Wizard’s Corner
The study of bones is known as osteology.
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THE SKELETON
The ribs are narrow curved bones that form a
cage to protect the heart and lungs. There are
12 pairs of ribs in a human being. A long bone
at the centre of the chest, called the sternum,
holds the ribs in place in the front. The ribs are
also attached to the backbone.
However, the last two pairs of ribs are attached
to our backbone and not the sternum. They are
called floating ribs.
Wizard’s Corner
Animals such as tigers and snakes have a backbone and
are called vertebrates. Animals such as earthworms and
cockroaches do not have a backbone and are called
invertebrates.
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THE RIBCAGE
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The backbone, known as the
spine or the vertebral
column, is attached to the
skull. It is made up of 33 small
bones. Each bone is called a
vertebra. The vertebrae can
move over each other. This
allows us to bend and twist
our back.
The spine is the central
supporting rod for the
skeleton and protects the
spinal cord, which is a thick
bundle of nerves.
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THE BACKBONE / SPINE
The upper arm has one long bone
called humerus. The lower arm has
two bones which are called the ulna
and the radius. The limbs are not
joined directly to the backbone, but
they are joined through girdles.
Girdles are the bony structures to
which the limbs of vertebrates are
attached.
The arms and legs are our limbs. The
bones of our limbs are very long.
Humerus
Femur
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1
2
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LIMBS
Pectoral
Girdles
Humerus
Femur
The thigh has a long bone. It is the
longest bone in our body and is
called femur. The leg has two
bones. The thighs are joined to the
spine by the hip girdle called pelvic
girdle. Many small bones make up
the ankle and the foot.
Pelvic
Girdles
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4
The upper arm is joined to the
spine by the collar bone and
shoulder girdle called the pectoral
girdle. The hand and the wrist have
many small bones.
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LIMBS
These joints provide free
movement of the body.
This is because of a fluid
known as synovial fluid,
present between the bones,
which acts like a lubricant.
The synovial fluid reduces
friction between the bones
of the joint so that they can
move easily.
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Synovial
fluid
Bones
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MOVABLE JOINTS
In a ball and socket joint, one end of the bone is like a ball that
fits into a hole or a socket of the other bone. Such a joint
allows free movement in all directions.
The shoulder joints and hip joints are examples of ball and
socket joints. They allow you to swing your arms and legs in
many different directions.
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BALL AND SOCKET JOINTS
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Gliding joints allow the bones to glide past one another in any
direction along the plane of the joint —up and down, left and
right, and diagonally.
Wizard’s Corner
Arthritis is a disease of the joints. It
causes inflammation, pain, swelling
and stiffness.
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GLIDING JOINTS
Click to add text
Muscles lie under the skin.
They are present in the heart,
digestive organs, and blood
vessels. They make our
heartbeat. They help us move
food in the food pipe and help
us chew our food. Muscles are
made up of a bundle of fibers.
Muscles not only help the body
parts to move but also give
them strength to do work.
They are attached to the bones
by strong fibers called tendons.
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MUSCLES
Muscles work by pulling or
contracting. Muscles cannot push.
Two sets of muscles work on a
joint to bring about the
movement.
The muscles of the upper arm are
called biceps and triceps.
When the biceps contract, the
triceps relax. This contraction and
relaxation of the muscles make the
bones move.
1
2
3
Biceps
contracts
Triceps
relaxes
Biceps
relaxes
Triceps
contracts
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HOW DOMUSCLES WORK?
There are three types of muscles in our
body: voluntary, involuntary and cardiac.
Voluntary or skeletal muscles are
attached to our skeleton and are under
our control. These muscles are found in
the arms, legs and eyes.
Involuntary muscles or smooth muscles
are not under our control. They work
automatically. They are found in our
stomach and intestine.
Cardiac or heart muscles are found in
the heart. They are involuntary and
work throughout our life without
stopping or getting tired.
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KINDS OFMUSCLES
Exercise is a good thing to improve muscle strength. You may have
observed that athletes and sportspersons have well-developed
muscles. You should also play outdoor games to keep your muscles
strong and in good shape. It is also important to maintain a correct
posture while walking, sitting or standing.
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Wizard’s Corner
There are about 640 muscles in our body,
which make up 40% of the body weight.
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TOMAINTAIN STRONG MUSCLES
A skeleton is the framework of bones
that gives shape, protects organs and
provides support to the body
The skeleton consists of bones of
different shapes and sizes.
The skull, spine, ribcage, limbs,
shoulder girdle and hip girdle are
parts of the skeleton.
Bones are hard on the outside, and
inside they contain bone marrow, a
soft and spongy matter, where red
blood cells are formed.
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3
4
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KEEP INMIND
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Joints help the bones to
move. They can be movable
or immovable.
There are 4 kinds of movable
joints: hinge, gliding, pivot,
and ball and socket.
Muscles help the bones to
move by pulling at them.
There are three kinds of
muscles - voluntary,
involuntary and cardiac.
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7
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KEEP INMIND
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ACTIVITIES
Activity 1: Press your hands on your chest, you will feel the
bones and not the lungs or the heart. In the same way try to feel
bones in other parts of your body.
Activity 2: Run your fingers along the central
portion of your back and feel the small
bones of the spine, arranged in a sequence.
Activity 3: Move your arms,
your legs, your wrists and your
head. This way you can feel the
working of different joints in
your body.
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ACTIVITIES
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MIND BUSTER
Does it hurt you when you break a bone?
Or when you hit your arm against
something hard?
What does this show?
What would happen if our backbone was
made of a single long bone, instead of many
small bones?
Name the parts of your body, where you have the following
joints: the gliding, the pivot, the ball and socket, the hinge joint.
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2
3
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MIND BUSTER
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VOCABULARY
biceps: muscles present in the upper arm that help us to bend at
the elbow
cardiac muscles: muscles present in the heart
involuntary muscles: muscles that are not under our control
joint: two or more bones meet to form a joint
ligament: connective tissue that joins one bone to another
tendon: connective tissue that joins a muscle to a bone
triceps: muscles present in the lower arm that help us to
straighten the elbow
voluntary muscles: muscles that are under our control
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VOCABULARY
